An attempt to control <Emphasis Type="Italic">Cameraria ohridella</Emphasis> using an attract-and-kill technique

This study estimates the efficacy of an attract-and-kill (A&K) technique to control the horse chestnut leaf miner, Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae), an invasive insect pest of the horse chestnut, Aesculus hippocastanum L. (Hippocastanaceae). The A&K formulation was dispensed as 50 μl droplets of paste-like matrix, containing C. ohridella sex pheromone, (8E,10Z)-tetradeca-8,10-dienal (85% + pure; 0.16% w/w) and a fast acting contact toxicant, pyrocides (94% pure; 6% w/w), applied directly to the bark of the trees. It was tested in 2003 at rates of 30 and 45 droplets/tree at the Ostrobramska site and at rates of 30, 60 and 90 droplets/tree at the Woloska site in Warsaw, Poland, for the first insect generation. A set of untreated plots (0 droplets/tree) was established at each site as well. The treatment efficacy was estimated using two indices: (1) moth catches in pheromone traps and (2) the number of mines per leaf. Trap catches were significantly higher in the untreated plots than in the treated plots regardless of the application rate in all sites. However, there were no significant differences in leaf damage amongst all plots on each site. At the “Lazienki Krolewskie” park the attractiveness of two types of pheromone sources were compared: traps were baited with rubber septum lures or with A&K droplets. The catches of C. ohridella in traps baited with lures were lower than captures in A&K droplet-baited traps, but the difference was not significant. Possible reasons for the low efficacy of the A&K method in management of C. ohridella and reducing leaf damage are discussed.     

Appearance and migration of the horse-chestnut leafminer Cameraria ohridella in relation to city size and leaf-raking, using the example of two cities in Western Poland

Possible differences in the size and dynamics of the appearance of particular generations of Cameraria ohridella were studied at two city sites of different size and character. The differences in the degree of infestation of Aesculus hippocastanum by the horse chestnut leafminer in the two towns are interpreted as a result of the differences in the size of food resources. The greater degree of infestation of trees in Mosina relative to trees in Pozna is most probably a result of the difficulty of aerial dispersion and thereby much stronger competition for food. This conclusion confirms a positive correlation of the distance between localities with the degree of tree infestation in a small town and the lack of such a correlation in a big city. The presence of refuges in the city outskirts at which no raking and removal of leaves is performed does not seem to have a significant effect on the degree of horse chestnut infestation in the centre.     

Mating disruption of the pink bollworm<Emphasis Type="Italic"> Pectinophora gossypiella</Emphasis> (Saund.) (Lepidoptera: Gelechiidae) using gossyplure PB-rope dispensers in cotton fields

The effects of mating disruption on population densities and percentage of damage of the pink bollworm Pectinophora gossypiella (Saunders) were investigated in a cotton field in central Greece, in 1992 and 1993. A 10-ha field was divided in two parts of 5 ha each. PB-rope dispensers were installed in mid-season in one part, whereas the other was used as a control field. Catches of pink bollworm moths in pheromone-baited traps and damage caused were recorded in both the treated and control fields. Results showed that moth catches were highly reduced in the treated field and, therefore, mid-season installation of dispensers was successful. Damage (%) was significantly less in the treated compared with the control field. Consequently, the field size of 5 ha seems to be adequate for the effective implementation of mating disruption.     

The effect of climate on radial growth of horse chestnut (<Emphasis Type="Italic">Aesculus hippocastanum</Emphasis> L.) in the Świętokrzyski National Park in central Poland

The objectives of this study were to construct a site tree-ring width chronology of horse chestnut (Aesculus hippocastanum L.) growing in a single locality situated in the Świȩtokrzyski National Park, and to determine its sensitivity to the two main climatic elements of air temperature and precipitation. Fifteen horse chestnut trees, growing on a moist site and not attacked by the leaf miner (Cameraria ohridella Deschka et Dimić), were selected for the study. Relationships between monthly values of air temperature, precipitation, and width of tree rings during 1932–2003 were analyzed, in addition to using bootstrapped response and correlation functions for single and multiple time intervals (the computer program DENDROCLIM2002 was used). High air temperature of the previous winter, as well as the air temperature of August of a given growing season positively affected the radial growth of horse chestnut. The cambium activity was also favored by ample precipitation in December preceding a given growing season. Excessive precipitation in August, which raised the existing high water table, had a negative effect on tree-ring width. The tree-ring chronology, elaborated for horse chestnut during this study, may be a local growth standard of this species. Thus, the model of climate–tree radial increment relationships may depend on characteristics of the locality where the trees are growing. Therefore, it would be advisable to undertake comparative studies.     

Parasitic Ichneumonoidea on the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae) in Slovakia

Parasitic Hymenoptera from the suprafamily Ichneumonoidea attacking the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) were studied in southwest Slovakia during 2000 and 2001. The search for such species resulted in the determination of eight ichneumonid species, Gelis agilis (Fabricius), Itoplectis alternans (Gravenhorst), I. clavicornis (Thompson), I. maculator (Fabricius), Scambus annulatus (Kiss), S. brevicornis (Gravenhorst), Zatypota percontatoria (Müller), Adelognathus sp. and a braconid Colastes braconius Haliday. The most abundant species was S. annulatus. All these species recorded are polyphagous and often facultative hyperparasitoids, except C. braconius, which departs from this norm in not being hyperparasitic. The presence of more diversified native parasitoids and hyperparasitoids from the Ichneumonoidea predicate a slow successive adaptation of the parasitoid fauna to the invasive host, Cameraria ohridella.     

Development of natural waxes dispensers for pheromones and use in mating disruption of the ambrosia beetle <Emphasis Type="Italic">Megaplatypus mutatus</Emphasis> in poplar (<Emphasis Type="Italic">Populus</Emphasis> spp) plantations

Megaplatypus mutatus (= Platypus mutatus) (Chapuis) is an ambrosia beetle native to South America that attacks live trees, mining deeply into the xylem through large tunnels. This activity weakens the structural integrity of the tree, causing severe stem-breakage and mortality. Attacks are initiated by pioneer males that select a host tree and build short nuptial galleries, to which they attract females using a sexual pheromone. Previously, we showed the potential for the strategy of pheromone-mediated mating disruption of M. mutatus in commercial poplar and hazelnut plantations in South America and Europe using polyethylene reservoir dispensers for pheromones. In the present work we replaced the polymeric reservoir dispensers by monolithic dispensers made by dispersion of the pheromone in natural waxes and the addition of kaolin and we found that: prior to pheromone deployment, the mean number of galleries per tree did not differ significantly between the control and treated plots and the same was observed after the mating disruption treatment for the control plot but not for treated plots, where the mean number of galleries were reduced. These findings confirm that mating disruption is a viable tool for management of M. mutatus in poplar plantations. Using natural wax dispensers has obvious advantages from an environmental point of view.     

Season-long mating disruption of <Emphasis Type="Italic">Grapholita molesta</Emphasis> (Lepidoptera: Tortricidae) by one machine application of pheromone in wax drops (SPLAT-OFM)

A novel emulsified wax dispenser (SPLAT-OFM) of pheromone was evaluated in concert with a custom-built, tractor-mounted applicator, designed for fast application of dispensers for mating disruption of Oriental fruit moth, Grapholita molesta (Busck), in apple. The formulation consisted of microcrystalline wax emulsified in water. It was loaded with G. molesta pheromone (93:6:1 blend of (Z)-8-dodecen-1-yl-acetate:(E)-8-dodecen-1-yl-acetate:(Z)-8-dodecen-1-ol) at 10% by weight. The hydraulically driven applicator dispensed the wax formulation as discrete particles from a rotating double-orifice distributor positioned directly above the tree canopy. Wax-drop size averaged (±SEM) 0.38 ± 0.16 g and 4.3 ± 0.5 drops adhered per tree. Following a single mechanized application of SPLAT-OFM on 24 April at 8 ml per tree (1.6 kg/ha) to 0.8 ha blocks of apple, male G. molesta orientation to optimally attractive pheromone traps was disrupted by 98% relative to untreated control plots for the whole season. Furthermore, on 17 weekly deployments of tethered virgin females (1,016 females deployed and 732 recovered for dissection) throughout the season, no mating was detected in SPLAT-OFM-treated blocks, while mating in control blocks averaged 27%. During the first 17 days following deployment in sticky traps, SPLAT-OFM drops attracted ca. 1/46th of the number of male G. molesta attracted to optimized synthetic lures. However, following 17 days of field aging, SPLAT-OFM drops became equally attractive to optimized synthetic lures for the remainder of the season. The release rate of pheromone from wax drops 0–14 and 15–76 days following deployment averaged 21.4 and 5.3 μg/h, respectively. The trapping and release rate data were consistent with competitive attraction as the mechanism mediating disruption. Shoot injury following the first moth generation was sevenfold less in SPLAT-OFM treated blocks compared with controls and fruit injury at the end of the season in treated blocks was approximately half of that recorded in controls.     

Acute spread in France of an invasive pest, the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae)

The horse chestnut leafminer, Cameraria ohridella Deschka & Dimic (Lepidoptera, Gracillariidae) spread over the last 10 years from central Europe to western Europe and was observed for the first time in 2000 in the east of France and near Paris. This study presents the results of surveys carried out in France in 2001 to investigate the distribution and infestation level of the leafminer. One year after its first discovery, the moth was present in a large part of the country and for the first time has been observed in Paris. The spread of the moth is due mainly to natural dispersal and to passive dispersal by human activities.     

Challenges of pheromone-based mating disruption of <Emphasis Type="Italic">Cydia strobilella</Emphasis> and <Emphasis Type="Italic">Dioryctria abietella</Emphasis> in spruce seed orchards

Seed orchards function as the primary source of high-quality seeds for reforestation in many European countries, but their seed yields can be severely reduced due to seed- and cone-feeding insects. We evaluated various parameters of pheromone-based mating disruption for control of the moths Cydia strobilella and Dioryctria abietella, which are major pests in European Picea abies seed orchards. We applied different types of pheromone dispensers (rubber septa or wax droplets) at different densities and heights, and with different amounts of active components, covering whole orchards or part of an orchard. The efficacy of the treatment was evaluated by analysing male captures in pheromone-baited assessment traps, and presence of larvae in cones. A dramatic decrease (94–100%) in capture of males in traps occurred in all pheromone-treated plots compared to control plots for both moth species. In contrast, a subsequent reduction in larval numbers in cones was only achieved when wax droplets were used as the dispensing formulation at high density and at the highest pheromone dose tested, and only in half of the trials for each pest species. Electrophysiological recordings using antennae of male C. strobilella indicated elevated pheromone concentrations in a treated plot versus a control plot. Our results show that mating disruption has potential to reduce cone damage in spruce seed orchards caused by C. strobilella and D. abietella, but optimisation of the technique is required to achieve consistent and efficient population suppression of these pests.     

Serological marking of <Emphasis Type="Italic">Pnigalio agraules</Emphasis> (Hymenoptera: Eulophidae) for field dispersal studies

The parasitoid wasp Pnigalio agraules (Wlk.) is a key natural enemy of the horsechestnut leafminer Cameraria ohridella Deschka and Dimić (Lepidoptera: Gracillariidae). As a basis for mark-release-recapture studies, aimed at investigating the dispersal of this parasitoid in the field, adults of P. agraules were marked using a vertebrate-specific immunoglobulin (IgG). The marker was later detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The IgG was either applied externally by spraying or internally by feeding an IgG-enriched diet. Different concentrations of the marker were used and the influence of abiotic (climatic conditions, time elapsed between marking and marker examination) and biotic factors (sex and age of the parasitoids) on the detection of the immunomarker was tested. External marking by spraying led to more homogeneous labelling than feeding the marker. Parasitoids labelled with 0.25 mg rabbit IgG per ten individuals contained enough immunomarker to be easily distinguished from unmarked ones. Neither the climatic conditions nor the sex or age of the insects had an influence on the detection of the marker. The IgG remained well detectable during the entire lifespan of the parasitoids, which was not negatively affected by the marking procedure. Serological marking can be used to investigate the dispersal behaviour of beneficial insects within mark-release-recapture studies.     

Expansion of dwarf bamboo, Sasa nipponica, grassland under feeding pressure of sika deer, Cervus nippon, on subalpine coniferous forest in central Japan

The long-term changes of the area of Sasa nipponica grassland, bark stripping damage to trees by sika deer, Cervus nippon, and sika deer densities on Mt. Ohdaigahara were assessed with aerial photographs, information from previous studies, and field experiments. The grasslands expanded year after year. The expansion rate was highest from 1982 to 1992, and lowest from 1992 to 1997. Bark-stripping damage on coniferous trees was heavier than that on broadleaf trees in both the early 1980s and 1998. The deer density in the eastern part of the area had been high (14.4–64.3 km⁻²) from 1984 until 1998. We presume that rich growth of S. nipponica and heavy feeding pressure by sika deer over the long term caused expansion of S. nipponica grasslands by killing canopy trees by bark stripping and preventing forest regeneration.     

Occurrence of common phyllosphere fungi of horse-chestnut (Aesculus hippocastanum) is unrelated to degree of damage by leafminer (Cameraria ohridella)

The horse chestnut leaf-miner (Cameraria ohridella Deschka & Dimi?, Lepidoptera, Gracillariidae) is an invasive pest causing extensive damage to leaves of the horse-chestnut (Aesculus hippocastanum L.) in Europe. In Lithuania, C. ohridella invaded in 2002 causing wilting, browning and premature fall of A. hippocastanum leaves. The aim was to get a better understanding of possible linkages between foliar fungal communities and leaf-miner damage in A. hippocastanum. Leaves of A. hippocastanum, differentially damaged by C. ohridella, were collected in 10 sites in Lithuania. The fungal communities were described through DNA isolation and amplification using an ITS rRNA marker and Ion Torrent-sequencing. Clustering of 214,897 high-quality sequences resulted in 1017 non-singleton fungal taxa, among which Aureobasidium pullulans (28.2% of all fungal sequences), Endoconidioma populi (27.7%), Phoma fungicola (11.3%), Cladosporium ramotenellum (7.6%) and Cryptococcus sp. 2185_4 (5.0%) were most common. Correspondence analysis showed that fungal communities from heavily and slightly damaged leaves were largely intermingled, showing that in both types of samples fungal communities were similar. In conclusion, the study demonstrated that the phyllosphere of A. hippocastanum is inhabited by a high diversity of fungal species, the majority of which constitute generalist endophytes, epiphytes and saprotrophic fungi. The occurrence of common phyllosphere fungi was unrelated to the degree of damage by C. ohridella.     

Evaluation of aerosol devices for simultaneous disruption of sex pheromone communication in <Emphasis Type="Italic">Cydia pomonella</Emphasis> and <Emphasis Type="Italic">Grapholita molesta</Emphasis> (Lepidoptera: Tortricidae)

A two-year study was conducted evaluating Puffer^® aerosol dispensers (Suterra LLC, Bend, OR, USA) for mating disruption of codling moth, Cydia pomonella (L.), and the oriental fruit moth, Grapholita molesta (Busck). The Puffer^® dispenser consists of a pressurized metal canister loaded with pheromone active ingredients dissolved in solvent and housed within a circuit-controlled, plastic dispensing cabinet programmed to release an aerosol spray of pheromone at regular intervals. Puffers^® were deployed at the label-recommended rate of 2.5 ha^?1 and released ca. 5–10 mg of pheromone (depending on treatment) per 15 min during a 12-h cycle beginning each day at 15:00 h for the duration of the season. In 2005, commercially-managed apple plots (3.2–4.9 ha) were treated with Puffers^® releasing both species’ pheromone simultaneously (dual-species) or with twice the number of adjacently-deployed Puffers^® (4–6 m apart) releasing each individual species’ pheromones (single-species), while maintaining comparable overall release rates of pheromone between these two treatments. Plots 100 m away and not treated with pheromone served as the control. Disruption of male C. pomonella and G. molesta orientation to pheromone-baited traps was 46–75 and 91–98%, respectively, in Puffer^®-treated plots compared with untreated controls. There was no statistical difference in moth disruption between plots treated with dual-species and single-species Puffers^®. Fruit injury was not statistically different between Puffer^®-treated plots and control plots not receiving pheromone. In 2006, disruption of male moth orientation to traps was 24–26 and 84–97% in Puffer^®-treated plots (2.9–5.7 ha) for C. pomonella and G. molesta, respectively, compared with untreated controls. During this season, fruit injury was lower in pheromone-treated plots compared with untreated controls at mid-season, but not at pre-harvest. Combining the pheromone of both species into single Puffer^® units did not decrease efficacy of disruption compared with deploying twice as many Puffers^® releasing a similar amount of each individual species’ pheromone suggesting that multi-species disruption using Puffers^® is a viable option. However, we conclude that the efficacy of disruption attained with low-densities (2.5 ha^?1) of Puffers^® at the moth densities recorded in this study is insufficient for effective control of C. pomonella without input of companion insecticides.     

Pre-exposure to sex pheromone did not affect mating behavior in the sweetpotato weevil <Emphasis Type="Italic">Cylas formicarius</Emphasis>

In sterile insect technique (SIT) programs, the released sterile males are important for their effectiveness. The use of sex pheromones to collect males is economical; however, pre-exposure to sex pheromones may affect male mating behavior, and would thus reduce the effectiveness of the SIT programs. Males exposed to sex pheromone may become attractive to other males due to pheromone adsorption on their body impregnation, prevent mating and reduce the dispersal of sterile males. We examined the effect of pre-exposure to sex pheromone on the mating behavior of male sweetpotato weevil Cylas formicarius. Pre-exposure to high-dose sex pheromone for 24 h did not affect the male mating behavior of C. formicarius, and the exposed males did not attract other males. These results suggest that male C. formicarius that were collected from a mass-rearing facility using sex pheromone can be effectively used in SIT programs.     

Calling behaviour and male response towards sex pheromone of poplar moth <Emphasis Type="Italic">Condylorrhiza vestigialis</Emphasis> (Lepidoptera: Crambidae)

The calling behaviour of virgin females Condylorrhiza vestigialis Guenée, 1854 (Lepidoptera: Crambidae) and the female pheromone gland extract activity were studied under laboratory conditions. Most of the females started calling from their first scotophase period after emergence. Maximum calling occurred between the seventh and tenth hours of the scotophase period. The length of the calling increased with age until the fourth scotophase, but the onset of calling time did not differ with age. The number of calling bouts increased significantly with age, but the mean duration of each calling bout (20.8 min) did not vary with age. Extracts of pheromone glands evaluated in a Y-tube olfactometer attracted significantly more males than control, 70 and 30%, respectively. Gas chromatographic–electroantennogram detection (GC–EAD) analysis of these extracts indicated the presence of a single EAD-active peak, the putative sex pheromone of the species. This pheromone compound may be suitable for monitoring populations densities of C. vestigialis, and for detection of the onset of the seasonal flight period. An efficient pheromone is of importance also with respect to current attempts to develop new control methods for this important pest of Populus spp. in Brazil.     

Phytophthora citrophthora,a new pathogen causing decline on horse chestnut in Turkey

Dieback symptoms were observed on horse chestnut trees planted approximately 40 years ago in Ankara, Turkey. Lesions at the stem bases of the affected trees were similar to those of ink disease on sweet chestnut. A Phytophthora sp. was isolated from the fine roots and soil samples collected around the stem bases by baiting using chestnut leaves. The pathogen was identified as Phytophthora citrophthora based on several morphological features and DNA sequences of the ITS region. Pathogenicity of P. citrophthora was tested by stem inoculation on 3‐year‐old horse chestnut saplings. P. citrophthora produced large cankers in 20 days and killed 40% of the saplings. This is the first report of P. citrophthora causing dieback on horse chestnut.     

Among-tree variation in leaf traits and herbivore attacks in a deciduous oak,Quercus dentata

Abstract

Variations in defensive and some other leaf traits were studied in a population of an oak species, Quercus dentata Thunberg, in northern Japan, with reference to attacks by ectophagous herbivores and leafminers. The oak population showed substantial individual variations in concentrations of total phenolics and condensed tannins, nitrogen content, trichome density, leaf area and budburst timing. With the exception of leaf mass per area, which showed a positive relation with leaf toughness and a negative relation with water content, no significant relation was observed between the plant traits studied, suggesting an absence of trade-off or linkage between them. The oaks also showed substantial individual variations in leaf area loss by ectophagous herbivores, densities of major leafminers (Phyllonorycter and Stigmella species) and survival of Phyllonorycter sap-feeding larvae. The density of trichomes showed a significant, negative relation with leaf area loss by ectophagous herbivores, but significant, positive relations with densities of some leafminers. The other leaf traits seldom showed significant relations with herbivore densities or survival. In this oak population, these traits may not have enough variations to be reflected in the abundance and performance of herbivores.     

<Emphasis Type="Italic">Lobesia botrana</Emphasis> males mainly fly at dusk: video camera-assisted pheromone traps and implications for mating disruption

Pheromone-mediated mating disruption (MD) is currently considered an effective strategy to control the European grapevine moth (EGVM), Lobesia botrana, with a successful interference on natural female calling during the male searching flight. However, little is known on the impact of the hour of the day on EGVM male flight. While various models forecasting the day of maximum presence of males per flight have been developed, field research on the male flight activity over 24 hours is scarce. Hence, we used video camera-assisted pheromone traps to allow a continuous monitoring of EGVM flights over daylight and night hours, quantifying captures of males. Experiments were carried out in three vineyards located in northern Spain over two years (2016 and 2017). Results showed that EGVM flight mainly occurred between 21:00 and 23:00 h (GMT+1, daylight saving time). Furthermore, male catches significantly differed over the study year, annual flight period and vineyard. Most of the dispensers used worldwide for EGVM MD continuously release the main sex pheromone component [(7E,9Z)-7,9-dodecadien-1-yl acetate], except for some automatic devices releasing puffs of sex pheromones at selected time intervals. The findings presented here can be useful to optimize the MD technique, identifying selected time intervals when the release of EGVM synthetic pheromones can be concentrated, boosting MD efficacy against this important pest, minimizing the release of synthetic sex pheromone molecules in the environment and reducing application costs.     

Timber harvest,damage to crop plants and yield reduction in two Costa Rican coffee plantations with Cordia alliodora shade trees

Both model and field estimations were made of the damage inflicted to coffee plants due to the harvest of timber shade trees (Cordia alliodora) in coffee plantations. Economic analyses were made for different coffee planting densities, yields, and both coffee and timber prices.Damage due to tree felling and log skidding should not be a major limitation to the use of timber shade trees in coffee plantations. The timber price that would balance all discounted losses and benefits to zero, for scenarios with and without trees ranged between 8–20 US $/m³ (current overbark log volume at the saw mill yard is US$ 66/m³). There will be lower margins for coffee damage in high yielding plantations, specially in years of good coffee prices. Nevertheless, the use of timber shade trees is recommended even in these scenarios.     

First evidence of deuterotokous parthenogenesis in the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), originates from South America and is now considered to be one of the most damaging invasive pests of tomatoes in the Mediterranean Basin countries of Europe and North Africa. The preventing pest mating control methods include: (1) the use of synthetic pheromones for male attraction and annihilation inside insecticide-containing traps; (2) mating disruption by saturating the atmosphere with sex pheromones which alter the ability of males to locate females; and (3) massive applications of sterile males to alter the overall reproductive success of the pest population. However, all these methods achieve only a poor success rate in controlling T. absoluta populations under greenhouse conditions. Sex pheromone management and sterile insect techniques are both based on an important biological trait: the insect must breed through sexual reproduction. Here, we report for the first time laboratory evidence of deuterotokous parthenogenesis, an asexual reproduction where both males and females are produced from unfertilized eggs. We discuss the consequences for T. absoluta control strategies.